Flexible coating formulations comprising a nonoxidizing substantially saturated non-volatile synthetic alkyd resinous vehicle



TENSILE STRENGTH- PSI April 8, 1969 R. ROLLES ETAL 3,437,612 FLEXIBLE COATING FORMULATIONS COMPRISING A NONQXIDIZING SUBSTANTIALLY SATURATED NON-VOLATILE SYNTHETIC ALKYD RESINOUS VEHICLE Filed Dec. 23, 1964 Sheet of 2 I ,L' m 20- E 3' E '6- Z 5 l2- COTTONSEED E g 8- SOYBEAN J I 1 1 COCONUT S BLANK l I I I I l I I00 200 300 400 500 4 8 I2 l6 HOURS IN WEATHER-OMETER DAYS RECOVERY X200 g 200 HOURS 5 I I Z 6 2 |2o 500 HOURS o I I I I I I 4 s |2|s2o242s EDGE-LIFTING IN MILLIMETERS FISH SOYBEAN w |soo- TUNG Q |2oo LINSEED 80o COTTONSEED COCONUT 400 INVENTORS ROLF ROLLES KENNETH E. LUYK ATTORNEY so I50 200 250 BY HOURS IN WEATHER-OMETER MODULUS OF ELASTICITY- (PSI) X ELONGATION PER CENT April 8, 1969 R. ROLLES ETAL FLEXIBLE COATING FORMULATIONS COMPRISING A NONOXIDIZING SUBSTANTIALLY SATURATED NON-VOLATILE SYNTHETIC ALKYD RESINOUS VEHICLE Filed Dec. 23, 1964 Sheet 6 of 2 FISH g1 36- sovaem 2 corroussso TUNG as- LINSEED cocowur 8- 40 so I20l60200 240 uouns m WEATHER-OMETER 5 20- COCONUT U \ii) I 6% 5 y g Q lg 'TUNG VSQYBEAN 5- FISH LINSEED COTTONSEED 2s- 40 80 I20 I 200 240 HOURS m WEATHER-OMETER COCONUT TUNG SOYBEAN L 1:7; 6

FISH \LINSEED WCOTTONSEED 0 INVENTORS o o o o o o ROLF ROLLES 3 g g g g g KENNETH E. LUYK ATTORNEY TENSILE STRENGTH PSI rum FLEXiiBLE COATING FORMULATIONS COMPRIS- ING A NONOXIDIZING SUBSTANTIALLY SAT- URATED N N -VOLATILE SYNTHETIC ALKYD RESINOUS VEHICLE Rolf Rolles, Allegheny Township, Westmoreland County, and Kenneth E. Luyk, Lower Burr-ell, Pa., assignors to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 23, 1964, Ser. No. 420,645 Int. Cl. (308;; 39/08; C09d 3/66 US. Cl. 26016 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates in general to new and improved synthetic resinous base coating formulations capable of providing, in applied and air-dried condition on underlying substrata, flexible and substantially crack-free cohesively and unitarily secured or attached protective and decorative film coatings.

The flexible nature of the coating formulations falling within the scope of the invention, in air-dried condition thereof, is of particular significance in their application as protective, and/or decorative, and weather-resistant coatings on at least the exposed surfaces of underlying substantially rigid substrata in that the air-dried or set coatings not only provide for unitary coextensive surface adherence, but also elastically adjust and follow changes in the surface contour of the substrata underlying the same, such as produced by denting, bending, warping, and similar encountered changes therein, without rupture, separation and/or cracking of the applied coatings.

The flexible and elastic properties exhibited by the airdried films of the coating formulations of the invention are also particularly advantageous in their application on inherently flexible substrata, such as composition shingles, siding, and similar roofing and building sheathing materials, where curling and edge-lifting are inherently present and are expected to occur on exposure of such materials to atmospheric changes. In this latter regard, several roofs shingled with as fabricated asphalt and similar conventional composition shingles have been coated and air-dried with the coating formulations of the invention, following several years exposure of the same, and the shingles so treated have been observed to curl and edgelift, and thereafter return to substantially fiat condition, in response to atmospheric changes, without developing surface lifting and cracking of, and/or permanent restraint by, the air-dried coating formulations on the ex posed surfaces of the shingles.

Bituminous and/or asphaltic base coatings, in attractive muted colors, have enjoyed universal acceptance, as coating formulations for application on flexible substrata, as early as 1957. However, the natural darkness in color of the bituminous or asphaltic vehicle components of these coating formulations left much to be desired in ited tates atent O "ice the range and permanence of coloration obtainable therewith. Wide experience with conventional unsaturated synthetic oxidizing and air-drying resinous coating formulations, and their well-known wider range of coloration adaptability, lead to their substitution for the complained of limited color effects obtainable with asphaltic or bituminous base coatings. However, such substituted unsaturated coating formulations were found to produce substantially non-flexible dried or hard set coatings which developed substantial cracking and permanent edge-lifting or edge-curling of flexible substrata on which the coatings had been applied, after relatively short periods of exposure.

The present invention is predicated on the discovery that a selected class of synthetic nonoxidizing substantially saturated resinous vehicle coating formulations can be substituted for the aforementioned bituminous or asphaltic base coating formulations, as well as for the unsaturated oxidizing synthetic resinous coating formulations, in formulating protective and decorative surface coatings for air-dried application on rigid as well as flexible substrata with substantial, and even complete, elimination of the narrow range of muted coloration associated with the asphaltic and equivalent vehicle coatings, as well as overcoming the surface cracking and permanent edge-curling propensities exhibited by dried or set unsaturated oxidizing synthetic resinous coating formulations, and this without the conventional practice of baking the substituted substantially saturated nonoxidizing synthetic resinous formulations so applied.

A two year laboratory and outdoor test program conducted for comparison of coating formulations incorporating asphaltic, synthetic oxidizing unsaturated resinous, as well as a broad and the selected class of synthetic nonoxidizing substantially saturated resinous vehicles of the present invention, has revealed an entirely new and improved coating system, incorporating the selected class of the latter vehicles, which overcomes all of the aforementioned drawbacks associated with asphaltic and synthetic unsaturated oxidizing resinous type coating formulations.

It is a primary object of the present invention to provide decorative and/or protective coating formulations which are characterized by their substantial freedom in air-dried film application from surface cracking, while being productive of a wide range of coloration.

A further object of the invention is to provide coating formulations of the above-stated characteristics in which the air-dried films or coatings thereof are substantially free from permanent edge-curling or edge-lifting of flexible substrata adherently supporting the same.

Another object of the invention is to provide protective coating formulations having their vehicle components selected in part or entirety from a selected class of synthetic alkyd resinous materials which are substantially saturated and nonoxidizing.

Other objects of the invention include the provision of air drying ready mixed or freshly mixed stable coating formulations consisting essentially of synthetic nonoxidizing substantially saturated resinous vehicles in combination with one or more conventional inert extenders and one or more metallic and/or nonmetallic hiding pigments, with and without additions thereto of at least one conventional insoluble tinting colorant, in compatible admixture.

Additional objects and advantages of the invention will be appreciated and understood by those skilled in the art to which the invention appertains on consideration of the following description, tabulated results and plots, in which:

FIG. 1 illustrates a graph or plot depicting comparative edge-lifting and recovery of flexible composition shingles coated with a variety of protective coating formulations, and following exposure testing of the same;

FIG. 2 illustrates a graph or plot depicting the effect of unsaturation index values of vehicles of a variety of coating formulations in relation to edge-lifting of surface coated flexible composition shingles exposed to accelerated weathering; and

FIGS. 3, 4, 5 and 6 illustrate graphs or plots depicting mechanical properties of freed or stripped air-dried protective coatings produced from the several coating formulations included in the curves of FIG. 1.

One of the chief discoveries and requirements attaching to the flexible coating formulations satisfying the practice of the invention concerns proper selection of the vehicle component thereof. For example, it was early discovered in the research and development of the invention that all vehicles, and particularly all nonoxidizing substantially saturated synthetic resinous vehicles, did not perform to provide uniformity in the flexibility and mechanical properties of air-dried coating formulations incorporating the same. On the other hand, the invention has established that coating formulations incorporating vehicles, of which at least percent by weight of the non-volatile component thereof consists essentially of nonoxidizing substantially saturated synthetic resinous vehicles containing or made from oils and oils of fatty acids characterized by having an iodine value within the range 1 to 60, were essential to the success of the invention.

The class of vehicles satisfying the flexible coating formulations of the invention in whole, and in at least 55 percent by weight of the non-volatile portion thereof, are the nonoxidizing substantially saturated synthetic resinous alkyd type vehicles, containing an oil having an iodine value within the range 1 to and broadly identifiable herein by the structural formulae:

wherein at least one fatty acid of the group consisting of lauric, myristic, pelargonic, palmitic, stearic, arichidrie and behenic, including those mixtures thereof in natural oils from which the vehicles are made, is present in each R position in the formulae; the polyfunctional alcohol portions of the formulae consist of at least one of the components glycerol, pentaerythritol, and dipentaerythritol; and the polyfunctional acid portions of the formulae consist of at least one of the group of acids consisting of phthalic, maleic, fumaric, succinic and adipic, as well as the anhydrides of such acids.

The iodine value within the range 1 to 60, characterizing the oils of the vehicles satisfying the coating formulations of the invention, has established the permissible and allowable degree of oxidization and unsaturation of vehicles capable of producing the flexible coating formulations of the invention.

Coating formulations incorporating the vehicles satisfying the invention have also been determined to exhibit mechanical properties, to be hereinafter described and illustrated in more detail, insuring such flexibility and elasticity of air-dried films or coatings of the same essential to the improved advantages and benefits of the invention.

The aforesaid chemical and structurally illustrated formulae establishing major characterizations of synthetic substantially saturated nonoxidizing resinous vehicles satisfying the coating formulations of the invention Will be more fully appreciated and understood on reference to Table I in which several vehicle oils have been identified and listed in terms of their origin, iodine values, and major fatty acid constituents expressed in percent by weight.

The iodine values for the oils listed in Table I have laid the basis for arriving at the iodine value range of l to 60 characterizing the oils and oils of fatty acids from which the selected class of nonoxidizing substantially saturated synthetic resinous vehicles satisfying the flexible coating formulations of the invention could be successfully formulated. Table I also establishes the basis for determining that the higher the iodine value of the oil from which the vehicle is made, the more susceptible a coating formulation containing or made therefrom will be to Oxidation, and the greater the change or variation in the mechanical properties of air-dried coatings during weathering of the same, as will be hereinafter revealed.

The class of nonoxidizing substantially saturated synthetic alkyd type resinous vehicles, and compatible mixtures thereof, containing and/or made from oil components having iodine values within the range 1 to 60, and satisfying the desired flexibility and mechanical properties of the coating formulations of the invention, are typified by the alkyd vehicles produced from coconut and similar oils and oil fatty acids, and compatible mixtures thereof. Vehicles made from such oils and oil fatty acids,

.such as the nonoxidizing substantially saturated synthetic alkyd type resinous vehicles, have been successfully modified by additions thereto of at least one of the compatible conventional diluent vehicle extends selected from the group consisting of cumarone indene resin, petroleum resin, styrene resin, esterified natural rosin, hydrocarbon resin, and cellulosic resins, in total amount by weight up to 45 percent of the non-volatile nonoxidizing substantially saturated alkyd vehicle portion of coating formulations satisfying the invention, without detracting from the desirable physical properties thereof.

Synthetic resinous vehicles incorporating the vehicle oils listed in Table I were employed in ready mixed paints or coating formulations prepared and tested in the development of the instant invention, and each of the vehicles of the so prepared coating formulations exhibited substantially the same iodine value as the oil from which it was formulated. Although only one of the coating formulations thus prepared, namely the formulation incorporating the coconut oil exhibiting an iodine value of between 8 to 10, was satisfactory in producing the flexible substantially crack-free air-dried coatings, characteristic of the invention, on accelerated laboratory and outdoor weather-exposure testing of the same, coconut oil has been satisfactorily blended in pro-per proportions with castor oil, having an iodine value of 81 to 91 and the major fatty acid constituents ricinoleic and oleic, to provide an oil component within the iodine value 1 to 60 in satisfaction of the practice of the invention. Similarly coconut oil can also be compatibly blended in proper proportions with the other oil bases listed in Table I to provide a satisfactory oil component within the iodine value range 1 to 60.

FIGS. 1 through 6 pictorially depict the results of accelerated weathering and mechanical laboratory testing of ready mixed paints or coating formulations prepared from the synthetic resinous vehicles incorporating each of the oils listed in Table I. The accelerated testing was conducted in a commercial laboratory type Weather-Ometer obtained from Atlas Electric Devices Company of Chicago, Ill., and was supplemented and confirmed by a series of outdoor exposure tests.

The coating formulations prepared from the vehicles containing the oils listed in Table I were applied and airdried on each of three specimens of substrata for: (1) outdoor exposure testing; (2) Weather-Ometer exposure testing; and (3) Weather-Ometer exposure and mechanical testing. For tests (1) and (2), the so formulated coatings were brushed on weathered conventional flexible composition asphalt shingles mounted over cedar panels. For the mechanical tests of (3), a uniform film coating of approximately twenty mils dry film thickness was applied over tin plated steel panels, allowed to dry in air at room temperature for three days, and thereafter the dry coating was stripped by amalgamation of the tin with mercury. The stripped or free coating films were thereafter exposed in the Weather-Ometer in triplicate to permit removal of single films at intervals for mechanical testing thereof.

Specific reference to the appended plots, or graphs, will reveal, in FIG. 1, edge-lifting versus Weather-Ometer exposure time for the flexible asphalt composition shingles coated with coating formulations prepared from vehicles containing the oils listed in Table I and identified therewith. A blank, or uncoated shingle, was included in the test of FIG. 1. It will also be quite apparent that the plots of FIG. 1 reveal the high superiority of the coating formulation incorporating the coconut oil synthetic nonoxidizing substantially saturated resinous vehicle, typified by the aforesaid alkyd resinous vehicle formulae and having an iodine value between 1 to 60.

The graphic results illustrated in the plots of FIG. 1 have provided data for curling or edge-lifting that have been used in conjunction with the unsaturation index of a vehicle, which is herein definable as the iodine value of the vehicle multiplied by the weight fraction of the fatty acids therein to lay the basis for the plots of FIG. 2. Therein it will be observed that two sloping straight lines show the relationship between the chemistry of a vehicle in coating formulations containing the same applied to the exposed surfaces of flexible asphalt shingles and exposed in the Weather-Ometer for 200 and 500 hours, with edge-lifting in millimeters plotted against the unsaturation index for the coating formulations incorporating vehicles formulated from the oils listed in Table I.

The relationship pictorially depicted in FIG. 2 clearly reveals and establishes that the lower the unsaturation index of a synthetic vehicle in a coating formulation, the lower edge-lifting propensities of flexible substrata on which coatings employing the vehicles have been applied. Table I and the plots of FIGS. 1 and 2 in turn further establish the desirable results and properties of the coating formulations of the invention incorporating synthetic resinous vehicles of the substantially saturated nonoxidizing type characterized by the iodine value 1 to 60.

The mechanical properties of the triplicate dry films or coatings removed or freed from the tin plated support panels, and thereafter exposed in the Weather-Ometer as hereinbefore described, were determined by cutting the stripped or freed films into /2 inch width strips and thereafter subjecting triplicate specimen strip-s thereof to tensile strength, modulus of elasticity, and elongation determinations at the end of 40, 120 and 240 hours in the Weather-Ometer. Similar determinations were also made on similar stripped coatings immediately following three days of drying at room temperature.

The results of the mechanical properties have been plotted in FIGS. 3, 4, 5 and 6 and it will be observed therefrom that the coatings incorporating vehicles containing the oils listed in Table I, in relation to the chemistry of each, is again apparent and established by test results. For example, unsaturated or highly oxidizable vehicles react in coating formulations incorporating the same to increase the tensile strength and modulus of elasticity of such coating formulations (FIGS. 3 and 4) as the airdried films are exposed to weather aging. On the other hand, there is little change in their initial elongation (FIGS. 5 and 6).

It will be further observed from FIG. 6 that practical significance attaches to tensile strength and elongation, as they relate to edge-lifting. In this regard the plots or curves of FIG. 6 clearly show that coating formulations made from unsaturated oxidizing or drying oil synthetic resinous vehicles, such as the vehicles containing cottonseed, linseed, fish, soybean and tung oils, and their associated fatty acids, the oils of which fall outside the iodine range of l to 60, develop strong cohesive forces, and on weathering, such coatings shrink on their underlying flexible substrata while becoming increasingly stronger.

The increasing tensile strengths eventually surpass the resisting strength of the flexible substrata, as well as exceeding the resisting strengths of many rigid substrata, particularly in areas subjected to bending and denting, while elongation of the coatings is relatively low, to thus provide a practically inelastic substantially rigid coating film, with edge-lifting permanent curling and surface cracking developing in the so surface-coated substrata.

In contrast, air-dried films or coatings of the substantially saturated nonoxidizing synthetic resin vehicle coating formulations of the invention (FIG. 6), repre sented by vehicles made from coconut oil, in accordance with the practice of the invention, are characterized by higher elongation, are therefore more elastic, and develop less strength with the net result that they do not react on weathering to pull up or permanently curl their underlying flexible substrata. Furthermore, the air-dried films of the coating formulations of the invention have shown little if any tendency to rupture and produce hairline surface cracking. In summation, the coating formulations incorporating the substantially saturated nonoxidizing synthetic resinous vehicles of the invention are characterized by low tensile strength and high elongation, as compared to coating formulations incorporating oil components falling outside the l to 60 iodine value.

Coating formulations satisfying and falling within the scope and intent of the invention, incorporating at least 55 percent by weight of the non-volatile vehicle portion thereof in the form of the substantially saturated nonoxidizing synthetic resinous non-volatile vehicles satisfying the above-included structural chemical alkyd formulae,

and exhibiting iodine values between 1 and 60, are admixable with hiding pigmentation and inert extenders, or bulking materials, in the coating formulations prepared therefrom in hiding pigment and inert extender solidsvolume concentrations of at least percent, and preferably within the hiding pigment and inert extender solidsvolume concentration range of 25 to 60 percent. In the herein expressed hiding pigment and inert extender solidsvolume relationship, further and positively defining and characterizing coating formulations falling within the scope of the invention, the expression hiding pigment and inert extender solids is inclusive of all solids in the coating formulations, other than the resinous vehicle solids, and by hiding pigment and inert extender solids-volume concentration is meant the relationship or ratio of the hiding pigments solids plus inert extender solids volume to total volume of all solids in the coating formulations of the invention.

The pigmentation portions of coating formulations falling within the scope of the invention are conventionally 2O referred to as hiding pigments to distinguish the same from the bulking or inert extenders employed in formulating the coatings, representatives of which pigments is at least one of the group of pigments consisting of metallic powders in general, and leafing and non-leafing alu- 25 minum flake powders specifically, zinc oxide, titanium oxide, iron oxide, chrome oxide green, chrome green, chrome yellow, umber, burnt sienna, and. similar materials. The inert extenders" or bulking materials referred to are represented by at least one of the group consisting of asbestos fibers, calcium carbonate, silicates, talc, alumina, mica, diatomaceous earths, and wood saw dust.

The inclusion of tinting colorants in the coating formulations of the invention, as distinguished from any distinctive coloration imparted by the hiding pigments thereof, encompass additions thereto of conventional compatible insoluble tinting organic and inorganic dry color pigments, colors-in-oil, flushed colors, and mixtures thereof, examples of which are phthalocyanine blue,

phthalocyanine green and toluidene red.

The following Table II includes a series of ten examples of coating formulations satisfying and falling within the scope of the invention, expressed on a percent by weight basis of the essential components listed therefor.

Percent Percent Percent Example Type of Oil Oil Phthalie Polyhydrie Anhydride Alcohol Coating compositions or formulations found in practice to support and satisfy the invention and exhibit the improved advantages and benefits thereof, basically consists essentially by weight of l to 34 percent hiding pigment; 3 to 40 percent inert extender, 4 to 40 percent nonvolatile vehicle, of which at least percent by weight must be a nonoxidizing substantially saturated synthetic alkyd resinous non-volatile vehicle containing an oil component having an iodine value of 1 to and the balance an inert resinous non-volatile diluent, and 40 to percent volatile hydrocarbon solvent; and said coating formulations being characterized -by having a hiding pigment and inert extender solids-volume concentration within the range 25 to 60 percent. In like fashion, and as previously stated, the non-volatile vehicle in the total amount of 4 to 40 percent, by weight, may be present in the coating formulations of the invention in the form of the nonoxidizing substantially saturated synthetic alkyd resinous non-volatile vehicle containing an oil component having an iodine value of l to 60.

At least one of the insoluble tinting colorants previously mentioned has been successfully added to the above coating formulations of the invention, in total amounts of .3 to 12 percent of the total weight thereof, and has been productive of a wide range of distinctively colored coating formulations falling within the scope of the invention.

Aromatic and aliphatic volatile hydrocarbon solvents, and admixtures thereof, has been satisfactorily employed in the coating formulations of the invention as the volatile solvent portion thereof. High flash solvent naphtha, toluol TABLE II.COATING FORMULATIONS ON PERCENT BY WEIGHT BASIS Hiding Pigment Tinting Colorant Inert Extender Vehicle Percent Non-Volatile Percent Percent Ex. Nonoxidizing Non-Volatile Volatile Type Percent Type Percent Type Percent Substantially Besinous Hydrocarbon Saturated Al- Diluent Solvent kyd Resinous Component Component Component 1 Titanium Dioxide 9.1 Phtlialocyaniue Blue 2.1 jf f gf gi f -g 22. 7 50.9

. Asbestos Fiber 8. 3 2 Aluminum Flakes..." 9.1 .-..do 2.1 Calcium Silicateflfl M 22.7 50.2 3 Titanium Dioxide--- 11.2 Flber 2:3 22.7 50.11 4 Aluminum Flakes..-" 11.2 2:3 22.7 50.11 5 do 6.9 Phthalocyanine 131110.... 1.6 29.1 50.0

9.5 10 4 -.do 2 4 g 2 26.0 43.1

9. i a i uiu m s i1 i t-,ute 25.2 i

s es 0s 1 er 1O 4 2 4 Calcium Silieate 8.0 i 437 9 Aluminum Flakes 10.6 1 {Asbestos Fiber 9.7 23 7 40 0 Titanium Dioxide..- 8.0 I"""""""'"'"""'"""" Calcium Silicate... 8.0 1o Aluminum mama. 10.4 Phthalocyanine Blue--. 2.1 S 1E 15.6 10.4 13.7

and xylol are typical aromatic hydrocarbons, whereas Varnish Makers and Painters naphtha and mineral spirits are typical of aliphatic hydrocarbons, satisfying the volatile hydrocarbon portions of the coating formulations of the invention.

The coating formulations or compositions of the invention can be further modified, without detracting from the improved properties and advantages thereof, by additions thereto of at least one conventional wetting agent, mildewcide, anti-flooding agent, as well as at least one conventional pressure and corrosion inhibitor, in total amounts by weight of 0.25 to 2.5 percent of the total weight of the coating formulations falling within the scope of the invention.

What is claimed is:

1. A coating formulation for application to produce an air-dried flexible coating on an exposed surface of substrata, said formulation consisting essentially by weight of 1 to 34 percent hiding pigment, 3 to 40 percent inert extender, 4 to 40 percent non-volatile vehicle at least 55 percent by weight of which is a nonoxidizing substantially saturated synthetic alkyd resinous nonvolatile vehicle; said alkyd resinous non-volatile vehicle having 16 to 24 percent of its weight in the form of polyfunctional alcohols consisting of at least one of the components glycerol, pentaerythritol and dipentaerythritol, together with 30 to 44 percent of its weight in the form of polyfunctional acids consisting essentially of at least one of the acids phthalic, maleic, fumaric, succinic, adipic and the anhydrides thereof, and the alkyd resinous non-volatile vehicle having 32 to 51 percent of its weight as coconut oil; and 40 to 70 percent volatile hydrocarbon solvent; and said coating formulation being characterized by a hiding pigment and inert extender solidsvolume concentration within the range 25 to 60 percent.

2. A coating formulation in accordance with claim 1 in which up to 45 percent by weight of the non-volatile vehicle is a compatible inert non-volatile diluent consisting essentially of at least one of the components cumarone indene resin, petroleum resin, styrene resin, esterified natural rosin, hydrocarbon resin and cellulosic resins.

3. A coating formulation in accordance with claim 1 in which the hiding pigment is titanium oxide pigment.

4. A coating formulation in accordance with claim 1 and including .3 to 12 percent by weight thereof of a compatible insoluble tinting colorant.

5. A coating formulation in accordance with claim 1 in which the hiding pigment is aluminum flake pigment.

6. A coating formulation in accordance with claim and including .3 to 12 percent by weight thereof of a compatible insoluble tinting colorant.

7. A coating formulation in accordance with claim 1 in which the inert extender is asbestos fiber.

8. A coating formulation in accordance with claim 7 and including .3 to 12 percent by weight thereof of a compatible insoluble tinting colorant.

9. A coating formulation in accordance with claim 1 in which the hiding pigment is nonleafing aluminum pigment.

10. A coating formulation in accordance with claim 9 and including .3 to 12 percent by weight thereof of a compatible insoluble tinting colorant.

11. A coating formulation in accordance with claim 1 in which the hiding pigment is nonleafing aluminum flake pigment and the inert extender is asbestos fiber.

References Cited UNITED STATES PATENTS 2,477,236 7/ 1949 Buchanan 106-282 2,642,404 6/ 1953 Pike 26040 2,857,344 r10/1958 Walus 26040 2,872,422 2/ 1959 Rolle et al. 260--22 2,877,130 3/1959 Caron et a1. 26022 2,886,459 5/1959 Lajoie 106281 2,980,638 4/1961 Polovina 260-22 3,085,890 4/1963 Rolles- 26040 3,128,260 4/ 1964 Langatroth 260-40 3,260,609 7/1966 Reeser 260-40 3,284,378 11/1966 Roberts 260-40 OTHER REFERENCES Chatfield: Varnish Constituents, Leonard Hill Limited, London, 1953, p. 85.

Patton: Alkyd Resin Technology Formulating Techniques and Allied Calculations, Interscience Publishers, New York, 1962, p. 20.

DONALD E. CZAJA, Primary Examiner.

R. W. GRIFFIN, Assistant Examiner.

Us. 01. X.R. 117-434, 167, 168; 260-22, 23, 23.3, 26, 33.6, 40 

